Method for determining rotation degree of cam on four-probe machine according to probe force

Abstract

The invention provides a method for determining the rotation degree of a cam on a four-probe machine according to a probe force, which comprises the following steps: acquiring a function relationship between the probe force applied to a sample and the distance between a probe tip and a stop gasket, and obtaining kp and bp according to the function relationship; obtaining a function relationship between the cam rotation angle and the probe height to obtain kc; a lower needle curve is tested on a machine table, and theta 0 is obtained; according to the following formula, theta t is obtained through calculation; # imgabs0 # Ft represents the target probe force, theta t represents the corresponding cam degree under the target probe force, kp and bp represent the slope and intercept of the position relation between the probe force and the needle tip and the locking gasket, theta 0 represents the cam degree when the locking gasket just makes contact with the sample, and kc represents the slope of the relation between the height where the probe is located and the rotation angle of the cam.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor testing technology, and in particular to a method for determining a cam rotation degree according to a probe force on a four-probe machine. Background Art

[0002] The four-probe test technology is widely used to monitor the quality or physical properties of thin film growth on-chip during the semiconductor integrated circuit process due to its ability to obtain relatively accurate material resistivity and sheet resistance. However, since the sheet resistance of some materials is extremely sensitive to external pressure, excessive pressure will cause damage to the sample, while too little pressure will cause deviation in the measurement results.

[0003] Therefore, how to accurately control the pressure applied by the four-probe on the sample to be tested is the focus of technical personnel in this field. Summary of the invention

[0004] The purpose of the present invention is to provide a method for determining the rotation degree of a cam according to the probe force on a four-probe machine, so as to accurately control the pressure applied by the four-probes on the sample to be tested.

[0005] In order to achieve the above object, the present invention provides a method for determining the rotation degree of a cam according to the probe force on a four-probe machine, comprising:

[0006] Obtain the functional relationship between the probe force applied to the sample and the distance between the probe tip and the stop pad, and obtain k according to the functional relationship p and b p ;

[0007] Get the functional relationship between the cam rotation angle and the probe height, and get k c ;

[0008] Test the needle lowering curve on the machine and obtain θ0;

[0009] According to the following formula, θ is calculated t ;

[0010]

[0011] F t represents the target probe force, θ t represents the cam degree corresponding to the target probe force, k p and b p represents the slope and intercept of the relationship between the probe force and the position between the needle tip and the stop washer, θ0 represents the cam degree when the stop washer just contacts the sample, k c The slope represents the relationship between the probe height and the cam rotation angle.

[0012] In the optional scheme, k is obtained according to the following functional relationship p and b p ,

[0013] F p =k p x pp +b p ;

[0014] Among them, F p represents the probe force (exerted by the probe on the sample), x pp Indicates the distance between the needle tip and the stop washer. When the needle tip is lower than the stop washer, x pp Is a negative number.

[0015] In the optional scheme, k is obtained according to the following functional relationship c

[0016] z=k c θ+b c ;

[0017] z is the distance between the probe and the sample, b c It represents the intercept of the relationship between the height of the probe and the rotation angle of the cam; θ represents the rotation angle of the cam.

[0018] In the optional solution, the method of testing the needle lowering curve on the machine to obtain θ0 includes:

[0019] The probe is mounted on the fixture, and the probe and the cam are connected by a mechanical mechanism. The sample is placed on the slide stage, and the rotation angle of the cam is controlled by software to drive the probe down. The height position of the stop washer is read by the displacement sensor to obtain the curve of the probe's descending height changing with the rotation angle of the cam.

[0020] As the cam rotates, the probe descends until the stop gasket contacts the sample. At this time, the probe will not descend further if the cam is rotated further. The degree of cam rotation corresponding to the first point when the probe height remains stationary is read as θ0.

[0021] The beneficial effects of the present invention are:

[0022] The present invention obtains k by testing p and b p , k c , θ0, and θ is calculated according to the formula t .

[0023]

[0024] During testing, the fixed cam degree is tested in this position. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which like reference numerals generally represent like components.

[0026] Figure 1 Schematic diagram of a partial structure of a four-probe measurement device in one embodiment of the present invention.

[0027] Figure 2 Schematic diagram of the positional relationship between the probe and the stop gasket in a top view in one embodiment of the present invention.

[0028] Figure 3 Schematic diagram of the longitudinal position relationship between the probe and the stop washer in one embodiment of the present invention.

[0029] Figure 4 Schematic diagram of the relationship between the lower needle height, the probe and the stop gasket position in one embodiment of the present invention.

[0030] Figure 5 It is a schematic structural diagram of a device for obtaining a curve of the relationship between probe pressure and the position between the probe and the stop gasket in one embodiment of the present invention.

[0031] Figure 6 for Figure 5 Function relationship curve obtained from device testing.

[0032] Figure 7 It is a schematic structural diagram of a device for obtaining the relationship between the probe height and the cam rotation angle in one embodiment of the present invention.

[0033] Figure 8 for Figure 7 Function relationship curve obtained from device testing.

[0034] Fig. 9 It is a structural schematic diagram of a device for obtaining a curve of a probe descending height changing with a cam rotating angle in one embodiment of the present invention.

[0035] Fig.10 for Fig. 9 The needle insertion curve obtained by device testing. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description and drawings, the advantages and features of the present invention will become clearer. However, it should be noted that the concept of the technical solution of the present invention can be implemented in a variety of different forms and is not limited to the specific embodiments described herein. The drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0037] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0038] Spatially relative terms such as "under," "below," "below," "under," "above," "above," etc., may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0039] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0040] Example 1

[0041] Reference Figures 1 to 10 This embodiment provides a method for determining a cam rotation degree according to a probe force on a four-probe machine, comprising:

[0042] Obtain the functional relationship between the probe force applied to the sample (the force applied by the probe to the sample) and the distance between the probe tip and the stop pad, and obtain k according to the functional relationship. p and b p ;

[0043] Get the functional relationship between the cam rotation angle and the probe height, and get k c ;

[0044] Test the needle lowering curve on the machine and obtain θ0;

[0045] According to the following formula, θ is calculated t ;

[0046]

[0047] F t represents the target probe force, θ t represents the cam degree corresponding to the target probe force, k p and b p represents the slope and intercept of the relationship between the probe force and the position between the needle tip and the stop washer, θ0 represents the cam degree when the stop washer just contacts the sample, k c The slope represents the relationship between the probe height and the cam rotation angle.

[0048] During the test, the cam degree is fixed at θ t When the device is not running, the cam is at 0 degrees and is constant. For the square resistance test of each point on the sample, the needle must be lifted up first (the cam is at 0 degrees), the stage is moved, and the point to be measured is moved to the bottom of the probe, and the cam is then turned down to θ t , and conduct the test.

[0049] Specifically, in a four-probe measuring device, the four-probe probe is usually fixed on a lifting frame, and is driven to move up and down by the rotation of a cam (in this embodiment, the cam is heart-shaped), and the height position of the probe can be read by a grating ruler. Therefore, for a certain cam, the relationship between the height of the probe and the rotation angle of the cam can be obtained.

[0050] In a four-probe probe, there is a stop gasket on each side of the four probes, and each probe is connected to a spring sheet. When the probe descends with the cam, the probe tip first contacts the sample. At this time, the elastic coefficient and contraction distance of the spring sheet determine the pressure applied by the probe to the sample until the stop gasket contacts the sample and the probe stops descending. For a four-probe probe, a curve of the probe force (pressure applied by the probe on the sample) and the position relationship between the needle tip and the stop gasket can be tested.

[0051] Therefore, through these relationships, the force applied by the four-probe probe to the sample to be measured can be accurately controlled by adjusting the cam rotation angle, and the four-probe measurement device can be optimized.

[0052] In this embodiment, it is assumed that the two stop washers are flat and symmetrical, the distances between the four needle tips and the stop washers are equal and x when the probes are not subjected to force, and the spring coefficients of the four probes are equal and k, a fixed value. When making the four-probe probe, the spring sheet elastic coefficient is adjusted to ensure that the force applied when the needle tip is parallel to the stop washers is 100g (single needle).

[0053] Assume that the deformation of the spring sheet is Δx, and Δx is equal to the distance that the cam continues to rotate and drives the probe to descend after the needle tip contacts the sample to be tested, which is a variable.

[0054] The corresponding probe force is

[0055] F Δx =kΔx+F0 (1)

[0056] Where F0 is the preload force of the spring sheet, a fixed value.

[0057] According to the force adjustment report of the corresponding probe obtained by the probe group (the following describes how to obtain the corresponding Figure 5 and Figure 6 ), we can get the actual functional relationship between the pressure and the distance between the needle tip and the stop washer, assuming it is (the subscript p is the probe, which is different from the theoretical derivation above):

[0058] F p =k p x pp +b p (2)

[0059] where x pp is the distance between the needle tip and the stop washer (subscript pp is probe & stop washer), and when the needle tip is lower than the stop washer, x pp Negative number (such as Figure 3 Therefore:

[0060] xpp=Δx--x(3)

[0061] Theoretically x pp = 0 means the stop gasket is in full contact with the sample, F p =b p =100g, so b p The theoretical value is 100.

[0062] From formulas (2) and (3), we can get:

[0063] F p =k p Δx+b p -kp x (4)

[0064] According to formulas (1) and (4), k p Equal to the spring coefficient k, (b p -k p x) is the preload force of the spring leaf.

[0065] The known quantities are: k p 、b p 、x.

[0066] After placing the sample, test the needle height curve, and take the degree θ0 corresponding to the first time when the needle height remains unchanged as the first point where the stop gasket contacts the sample.

[0067] The functional relationship between the cam rotation angle and the probe height is known (the following describes how to obtain it, corresponding to Figure 7 and Figure 8 ), and when the degree range is from 32.5° to 147.5°, the degree and the distance between the probe and the needle change linearly. According to experience, the probe contacts the sample when the cam degree is 60°-80°, and is fully in contact when the degree is 120°, that is, the probe is parallel to the stop gasket, so the degree and the distance between the probe and the needle change linearly when the sample force changes from 0 to 100g.

[0068] If we need to obtain the target probe force F t (subscript t is target), then according to formula (4) we can get:

[0069]

[0070] Target needle height z t The relationship between the spring deformation Δx is as follows ( Figure 4 shown):

[0071] z t =z0-x+Δx (6)

[0072] Where z0 is the needle height corresponding to the cam degree θ0, z t The height difference between the stop pad position when the ideal probe force is achieved and the stop pad position when the cam rotates 0 degrees, and according to the slope k c You can get:

[0073] z t -z0=k c (θ t -θ0) (7)

[0074] where θ t is the target cam degree.

[0075] Substituting formulas (5) and (7) into (6), we can obtain:

[0076]

[0077] θ0 is the cam angle when the stop gasket just contacts the upper sample. The following describes how to obtain it.

[0078] Reference Figure 5 and Figure 6 , test the probe group, obtain the force adjustment report of the corresponding probe, and obtain the functional relationship between the probe force applied to the sample and the distance between the probe tip and the stop washer.

[0079] 1. Fix the probe on the fixture.

[0080] 2. Adjust the probe position by using the front, back, left, and right knobs so that the push-pull force gauge is aligned with the stop washer, adjust the up and down knobs, and return the micrometer to zero when the push-pull force gauge displays 0.

[0081] 3. Adjust the probe position so that the dynamometer is aligned with the other stop washer. At this time, both the dynamometer and micrometer should display 0.

[0082] 4. Adjust the probe position so that the push-pull force gauge is aligned with a needle tip. When the micrometer is at 0, observe whether the push-pull force gauge displays 100g. If not, adjust the spring sheet connected to the probe.

[0083] 5. Adjust the probe position up and down, and read the micrometer reading and the push-pull force gauge reading at the same time, and you can get the curve of the probe force and the position relationship between the probe and the stop washer. Since the elastic coefficient of the spring sheet remains unchanged, the two are in a linear relationship, such as Figure 6 As shown, we can get F p =k p x pp +b p Among them, F p represents the probe force (the force applied by the probe to the sample), x pp Indicates the distance between the needle tip and the stop washer. When the needle tip is lower than the stop washer, x pp Is a negative number.

[0084] Reference Figure 7 and Figure 8 , obtain the functional relationship between the cam rotation angle and the probe height (i.e. the relationship between the cam degree and the step value).

[0085] 1. The mechanical structure between the fixture and the cam is used to fix the probe.

[0086] 2. Use software to control the cam rotation angle, use a micrometer to read the distance the fixture descends, and obtain the relationship between the probe height and the cam rotation angle. The obtained curve is as follows: Figure 8As shown, the horizontal axis is the cam rotation angle, and the vertical axis is the fixture lowering distance.

[0087] 3. Since the contact between the probe and the sample corresponds to the linear segment in the figure, the cam step value can be obtained similar to z = k c θ+b c z represents the distance between the probe and the sample, b c It represents the intercept of the relationship between the height of the probe and the rotation angle of the cam; θ represents the rotation angle of the cam.

[0088] Reference Fig. 9 and Fig.10 , test the needle lowering curve on the machine and obtain θ0.

[0089] 1. Install the probe on the fixture. Connect the probe and cam through a mechanical mechanism. Place the sample to be tested on the slide stage.

[0090] 2. The cam rotation angle is controlled by software to drive the probe down, and the height position of the stop washer is read by the grating ruler.

[0091] 3. Obtain the curve of the probe's descending height changing with the cam's rotation angle, such as Fig.10 , the horizontal axis is the cam rotation angle, and the vertical axis is the stop pad height position read by the grating ruler. As the cam rotates, the probe descends until the stop pad contacts the sample to be tested. At this time, the probe will not descend further if the cam is rotated further until the probe is lifted up as the cam rotates more than half a circle.

[0092] 4. Read the cam rotation degree θ0 corresponding to the first point when the probe height remains stationary, and assume that the stop gasket just contacts the sample to be tested at this time, that is, the probe force is 100g.

[0093] In this embodiment, the rotation degree of the cam is calculated according to the target probe force. Since the rotation degree of the cam is related to the probe height, that is, the probe height is calculated, this embodiment can accurately control the pressure applied by the four probes on the sample to be tested.

[0094] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for determining the rotation degree of a cam based on probe force on a four-probe machine, characterized in that: include: Obtain the functional relationship between the probe force applied to the sample and the distance between the probe tip and the stop pad, and obtain k according to the functional relationship p and b p ; Get the functional relationship between the cam rotation angle and the probe height, and get k c ; Test the needle lowering curve on the machine and obtain θ0; According to the following formula, θ is calculated t ; F t represents the target probe force, θ t represents the corresponding target probe force, k p and b p represents the slope and intercept of the relationship between the probe force and the position between the needle tip and the stop washer, θ0 represents the cam degree when the stop washer just contacts the sample, k c The slope represents the relationship between the probe height and the cam rotation angle.

2. The method for determining the rotation degree of a cam according to the probe force on a four-probe machine according to claim 1, characterized in that: According to the following functional relationship, k is obtained p and b p , F p =k p x pp +b p ; Among them, F p represents the probe force, x pp Indicates the distance between the needle tip and the stop washer. When the needle tip is lower than the stop washer, x pp Is a negative number.

3. The method for determining the rotation degree of a cam according to the probe force on a four-probe machine according to claim 1, characterized in that: According to the following functional relationship, k is obtained c , z=k c θ+b c 4 z is the distance between the probe and the sample, b c It represents the intercept of the relationship between the height of the probe and the rotation angle of the cam; θ represents the rotation angle of the cam.

4. The method for determining the rotation degree of a cam according to the probe force on a four-probe machine according to claim 1, characterized in that: The methods for testing the needle-dropping curve on the machine and obtaining θ0 include: The probe is mounted on the fixture, and the probe and the cam are connected by a mechanical mechanism. The sample is placed on the slide stage, and the rotation angle of the cam is controlled by software to drive the probe down. The height position of the stop washer is read by the displacement sensor to obtain the curve of the probe's descending height changing with the rotation angle of the cam. As the cam rotates, the probe descends until the stop gasket contacts the sample. At this time, the probe will not descend further if the cam is rotated further. The degree of cam rotation corresponding to the first point when the probe height remains stationary is read as θ0.

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